Fulton County sheriff’s spokeswoman Tracy Flanagan said Tuesday a gun no bigger than a cell phone was found in the area where the two had a dispute. She says the injured inmate was treated at the jail for non-life threatening injuries.

Flanagan says the gun was “not a county-issued weapon.”

Authorities offered no explanation on how the gun got inside the Fulton County Jail.

The jail was placed on lockdown, and some employees and visitors in the lobby were evacuated.

Flanagan says the suspect is a 28-year-old inmate from Atlanta in his 14th stay at the jail since 2000.

A photo of the inmate, Kortez Hurt, responsible for firing the weapon is posted below.